The Legendary K.O. samples Kanye West, who uses a fragment from Ray Charles, who may have taken material from Will Lamartine Thompson or, more likely, from Clara Ward (who herself borrowed from a gospel standard). The chain of borrowing I describe here has one end in the hymns and spirituals of the early 1900s and the other in the twenty-first century’s chaotic stew of digital sampling, remix, and mashup. Along the way, we have the synthesis of old and the invention of new musical genres—often against the wishes of those whose work is serving as the raw material... Far from building everything anew, these musicians seem quite deliberately to base their work on fragments taken from others...

This definitely had my interest and I was doing some searching when I came across this interview with Ray Charles by Johnny Carson:

Johnny asks a great question at 2:43 of the interview, "You haven't done any rap yet have you?" and Charles tells Johnny how we think, create, and build upon the works of others. This is how we construct new knowledge. Sense-making in action. And of course, the way Charles learned would probably be illegal today. His work would be driven underground. He'd still find a way to create just not in a way that the whole of society would benefit. The exact opposite effect from what copyright was intended to enable.